Technical Field
The present invention relates to an image generation apparatus, method, and program that generates a pseudo three-dimensional image by performing volume rendering on a three-dimensional image.
Background Art
Heretofore, processing for generating and displaying a pseudo three-dimensional image has been performed in which three-dimensional image data of a subject obtained by CT equipment, MRI equipment, ultrasonic diagnostic equipment, or the like are stereoscopically visualized on a two-dimensional plane using computer graphics technologies in order to facilitate understanding of a three-dimensional structure of the subject and the like. As a method for generating such a pseudo three-dimensional image, a volume rendering method is known in which opacity and color information of R, G, B are set to each pixel value (voxel value) constituting a three-dimensional image and the visualization is achieved by performing ray-casting on each pixel on a projection plane from the observation side.
For the opacity or color information set (referred to as opacity curve and color map respectively) which is set to each pixel value, it is common to give one set to one three-dimensional image. But this causes a problem that different tissues having the same signal value cannot be displayed distinguishably. In response to this, when generating one image representing a plurality of objects (e.g., bone, blood vessel, heart, liver, and the like) by volume render, a literature, H. Imai, “I see! ! The Bible of the Way of Thinking and Processing—Three-Dimensional Medical Image”, Shujunsha, P. 105, 2003, proposes that different tissues having the same signal value are represented by different color or opacity by applying a different color map and/or opacity curve to each object region.